Orygen, The National Centre of Excellence in Youth Mental Health, Melbourne, Australia. pbadcock@unimelb.edu.au.

4

Australian Research Centre in Sex, Health and Society, La Trobe University, Melbourne, Australia.

5

Centre for Positive Psychology, Melbourne Graduate School of Education, University of Melbourne, Melbourne, Australia.

6

School of Public Health, University of Sydney, Sydney, Australia.

7

Social Research Centre, Melbourne, Australia.

8

School of Psychology, University of Sussex, Sussex, UK.

9

Kirby Institute, University of New South Wales, Sydney, Australia.

10

School of Public Health and Community Medicine, University of New South Wales, Sydney, Australia.

Abstract

This study investigated differences between the demographic characteristics, participation rates (i.e., agreeing to respond to questions about sexual behavior), and sexual behaviors of landline and mobile phone samples in Australia. A nationally representative sample of Australians aged 18 years and over was recruited via random digit dialing in December 2011 to collect data via computer-assisted telephone interviews. A total of 1012 people (370 men, 642 women) completed a landline interview and 1002 (524 men, 478 women) completed a mobile phone interview. Results revealed that telephone user status was significantly related to all demographic variables: gender, age, educational attainment, area of residence, country of birth, household composition, and current ongoing relationship status. In unadjusted analyses, telephone status was also associated with women's participation rates, participants' number of other-sex sexual partners in the previous year, and women's lifetime sexual experience. However, after controlling for significant demographic factors, telephone status was only independently related to women's participation rates. Post hoc analyses showed that significant, between-group differences for all other sexual behavior outcomes could be explained by demographic covariates. Results also suggested that telephone status may be associated with participation bias in research on sexual behavior. Taken together, these findings highlight the importance of sampling both landline and mobile phone users to improve the representativeness of sexual behavior data collected via telephone interviews.